Explaining the RKR_{K} and RD(∗)R_{D^{(*)}} anomalies with vector leptoquarks

Recently the $B$ factories BaBar and Belle as well as the LHCb experiment have reported several anomalies in the semileptonic $B$ meson decays such as $R_{K}$ and $R_{D^{(*)}}$ etc. We investigate these deviations by considering the vector leptoquarks relevant for both $b \to s l^+ l^-$ and $b \to c l \bar \nu_l$ transitions. The leptoquark parameter space is constrained by using the experimentally measured branching ratios of $B_s \to l^+ l^-$, $\bar B \to X_s l^+ l^- (\nu \bar \nu)$ and $B_u^+ \to l^+ \nu_l$ processes. Using the constrained leptoquark couplings, we compute the branching ratios, forward-backward asymmetries, $\tau$ and $D^*$ polarization parameters in the $\bar B \to D^{(*)} l \bar \nu_l$ processes. We find that the vector leptoquarks can explain both $R_{D^{(*)}}$ and $R_K$ anomalies simultaneously. Furthermore, we study the rare leptonic $B_{u, c}^* \to l \bar\nu$ decay processes in this model.Comment: 33 pages, 14 figures, typos correcte

Probing Dual NSI and CP Violation in DUNE and T2HK

The latest results from the long baseline neutrino experiments show a hint of non-zero CP violation in the neutrino sector. In this article, we study the CP violation effects in the upcoming long-baseline neutrino experiments DUNE and T2HK. Non-standard interactions can affect the cleaner determination of CP violation parameter. It has been argued that the NSI can help alleviate the tension between the recent $\delta_{CP}$ measurements of NO$\nu$A and T2K experiments. We consider here the dual NSI due to $\epsilon_{e\mu}$ and $\epsilon_{e\tau}$, arising simultaneously to see the effects in neutrino oscillation probabilities. Moreover, the CP asymmetry parameter $A_{CP}$ exhibits a clear distinction between normal and inverted mass orderings in the DUNE experiment.Comment: 30 pages, 46 figures. arXiv admin note: text overlap with arXiv:2302.0959

Scalar triplet leptogenesis in the presence of right-handed neutrinos with S3 symmetry

Leptogenesis appears to be a viable alternative to account for the baryon asymmetry of the universe through baryogenesis. In this context, we consider a scenario in which the standard model is extended with $S_3$ and $Z_2$ symmetry in addition to the two scalar triplets, two scalar doublets and three right handed neutrinos. Presence of scalar triplets and right-handed neutrinos in the scenarios of both type-I and type-II seesaw framework provide a different leptogenesis option and can help us to understand the matter-antimatter asymmetry with simple $S_3$ symmetry. We discuss the neutrino phenomenology and leptogenesis in both high ($O(10^{10})$ GeV) and low energy scale ($O$(2)TeV) by constraining the Yukawa couplings. Moreover, we also consider the constraints on model parameters from neutrino oscillation data and leptogenesis to explain the rare lepton flavor violating decay and muon g-2 anomaly.Comment: 32 pages, 10 figure

Perturbative Bottom-up Approach for Neutrino Mass Matrix in Light of Large \theta_{13} and Role of Lightest Neutrino Mass

We discuss the role of lightest neutrino mass (m_0) in the neutrino mass matrix, defined in a flavor basis, through a bottom-up approach using the current neutrino oscillation data. We find that if m_0 < 10^{-3} eV, then the deviation \delta M_\nu in the neutrino mass matrix from a tree-level, say tribimaximal neutrino mass matrix, does not depend on m_0. As a result \delta M_\nu's are exactly predicted in terms of the experimentally determined quantities such as solar and atmospheric mass squared differences and the mixing angles. On the other hand for m_0 \gsim 10^{-3} eV, \delta M_\nu strongly depends on m_0 and hence can not be determined within the knowledge of oscillation parameters alone. In this limit, we provide an exponential parameterization for \delta M_\nu for all values of m_0 such that it can factorize the m_0 dependency of \delta M_\nu from rest of the oscillation parameters. This helps us in finding \delta M_\nu as a function of the solar and atmospheric mass squared differences and the mixing angles for all values of m_0. We use this information to build up a model of neutrino masses and mixings in a top-down scenario which can predict large \theta_{13} perturbatively.Comment: 26 pages, 42 eps figures, revtex (references are added, more discussions are added in section-III

Hadronic Decay of Bc Meson to Pseudoscalar and Vector mesons using the Isgur-Scora-Grinstein-Wise Model

The extensive study of B meson decays has led to precise measurements of the standard model parameter

Neutrino Physics: Leading Pathway to New Discovery

In this project i have discussed about neutrino oscillation in matter and its implication on astrophysical objects e.g.neutron star

Flavour physics and CP violation

It is well known that the study of flavour physics and CP violation is very important to critically test the Standard Model and to look for possible signature of new physics beyond it. The observation of CP violation in kaon system in 1964 has ignited a lot of experimental and theoretical efforts to understand its origin and to look for CP violation effects in other systems besides the neutral kaons. The two B-factories BABAR and BELLE, along with other experiments, in the last decade or so made studies in flavour physics and CP violation a very interesting one. In this article we discuss the status and prospectives of the flavour physics associated with the strange, charm and bottom sectors of the Standard Model. The important results in kaon sector will be briefly discussed. Recently, mixing in the charm system has been observed, which was being pursued for quite some time without any success. The smallness of the mixing parameters in the charm system is due to the hierarchical structure of the CKM matrix. Interestingly, so far we have not found CP violation in the charm system but in the future, with more dedicated experiments at charm threshold, the situation could change. Many interesting observations have been made in the case of bottom mesons and some of them show some kind of deviations from that of the Standard Model expectations which are mainly associated with the b → s flavour changing neutral current transitions. It is long believed that the B s system could be the harbinger of new physics since it is a system in which both bottom and strange quarks are the constituents. Recently, D0 and CDF announced their result for the B s mixing which is claimed to be the first possible new physics signature in the flavour sector. We plan to touch upon all important issues pointing out both theoretical and experimental developments and future prospects in this review article

Effective theory approach to new physics in b→u and b→c leptonic and semileptonic decays

Recent measurements of exclusive B-→τ-ν and B0→π+l-ν̄l decays via the b→ulν transition process differ from the standard model expectation and, if they persist in future B experiments, will be a definite hint of the physics beyond the standard model. Similar hints of new physics have been observed in b→c semileptonic transition processes as well. BABAR measures the ratio of branching fractions of B→(D,D*)τν to the corresponding B→(D,D*)lν, where l represents either an electron or a muon, and finds 3.4σ discrepancy with the standard model expectation. In this context, we consider a most general effective Lagrangian for the b→ulν and b→clν transition processes in the presence of new physics and perform a combined analysis of all the b→u and b→c semi-(leptonic) data to explore various new physics operators and their couplings. We consider various new physics scenarios and give predictions for the Bc→τν and B→πτν decay branching fractions. We also study the effect of these new physics parameters on the ratio of the branching ratios of B→πτν to the corresponding B→πlν decays